OP0273 LONGITUDINAL TRAJECTORIES OF RENAL FUNCTION IN ANCA-ASSOCIATED VASCULITIS: FINDINGS FROM THE EXPANDED MASS GENERAL BRIGHAM COHORT
Authors: J. Hanberg, C. Cook, X. Fu, H. Choi, Y. Zhang, Z. Wallace
Journal: Annals of the Rheumatic Diseases (2023)

<h3>Background</h3> Renal vasculitis, leading to a spectrum of chronic kidney disease (CKD) and end-stage renal disease (ESRD), is common in ANCA-associated vasculitis (AAV). The longitudinal course of renal dysfunction in AAV has only recently been described quantitatively.(1, 2) <h3>Objectives</h3> To confirm and further describe the longitudinal trajectory of renal function in an expanded AAV cohort. <h3>Methods</h3> We included patients from the Mass General Brigham AAV cohort, a consecutive inception cohort (2002-2022). We required at least 2 measurements of renal function including one "baseline" measurement (+/- 30 d from treatment initiation date, the index date). Renal function was assessed up to monthly between -12 m and +24 m relative to the index date. We used group-based trajectory modeling to identify renal function trajectories. Between-group differences (between all 4 groups) were assessed using the chi-square test and Kruskall-Wallis tests; time to ESRD was compared using the log-rank test. <h3>Results</h3> Among 375 patients, we identified 4 renal trajectory groups: rapid decline (N=23 [6%]), impaired (N=109 [29%]), preserved (N=216 [58%]), and recovery (N=27 [7%]) (<b>Figure 1</b>). Median posterior probability of group membership was &gt;0.99, indicating excellent model fit. Age, sex, race and ANCA type were not statistically different between groups. Baseline comorbidity (by Charlson Comorbidity Index) was highest in the rapid decline group, and higher in the impaired compared to the preserved and recovery groups (p&lt;0.001; <b>Table 1</b>). There was a strong trend toward hypertension being more common in the rapid decline and recovery groups vs the impaired and preserved groups (p=0.06). The baseline Birmingham Vasculitis Activity Score was higher in the rapid decline (6 [4, 7]) and recovery (6 [4, 9]) groups, compared to the impaired (5 [4, 6.5]) and preserved (4 [3, 6]) groups (p&lt;0.001). ESRD occurred in 49 patients, including 22 (96%) in the rapid decline group, compared to 11 (10%) in impaired, 15 (7%) in preserved and 1 (4%) in the recovery group. Median time to ESRD was &lt;1 m in the rapid decline group vs 3.5 y (IQR 0, 6.8) in impaired and 2.5 y (IQR 0, 5.6) in the preserved group (log-rank p&lt;0.001). ESRD was attributed to active AAV in 91% of cases in the rapid decline group, compared to 45% of impaired and 33% of the preserved group (p=0.01). Clinically significant CKD (eGFR&lt;30 ml/min/1.73m2) was present in a majority of the impaired group at 1, 2 and 5 y, but was less common in the preserved group (p&lt;0.001 at all 3 timepoints). <h3>Conclusion</h3> We confirmed 4 distinct renal trajectory groups in an expanded AAV cohort. Trajectory groups were distinguished by differences in baseline comorbidity, rates of ESRD and CKD, and etiology and timing of ESRD. These findings emphasize the need for additional studies investigating temporal factors mediating these associations. <h3>References</h3> [1]Lionaki S, et al. <i>Kidney international.</i> 2009;76(6):644-51. [2]Hanberg J, et al. <i>Arthritis Care Res.</i> 2023; In Press. <h3>Acknowledgements:</h3> NIL. <h3>Disclosure of Interests</h3> None Declared.